I had the same issue, unfortunately my washing machine does not have an API. I used a raspberry Pi with a camera, using OCR i was able to detect the remaining time from the display. Having an API like this would have been so much easier.
I did create an opensource web app so you are able to see your remaining time, laundry history, and get (push/mail) notifications. Since you only need to push the remaining seconds to an http endpoint it probably is easy to use with the solution described in the article.
Ofcourse, with only xbmc the default web interface and app are good enough, i agree.
But when you have 5 programs running, on your htpc and for every one you have to use a different interface, HtpcManager can provide a solution by combining all programs into one interface.
This project runs great on a raspberryPi (that is how i use it myself). I would recommend doing a git clone the get Htpc Manager running on the Pi. This makes auto-updating the htpc manager software a lot easier.
I did create an opensource web app so you are able to see your remaining time, laundry history, and get (push/mail) notifications. Since you only need to push the remaining seconds to an http endpoint it probably is easy to use with the solution described in the article.
https://github.com/styxit/laundry-admin